47 die in South Korea landslides

South Korean soldiers remove debris at a damaged apartment after a landslide caused by heavy rains in Seoul (AP)

Vehicles are submerged in floodwater after heavy rain in Seoul, South Korea (AP)

Thousands of rescuers in the South Korean capital of Seoul have been digging through thick mud for survivors of deadly landslides and flooding as the military warned that buried land mines may have slid down mountains pummelled by rain.

Massive rainfall in Seoul and surrounding areas since Tuesday has killed at least 47 people, including 10 college students engulfed by a landslide. Another four people are missing.

Efforts to dig for the missing took a dangerous turn when the Defence Ministry said mines could have shifted down a mountain hit by a landslide in southern Seoul.

Yoon Yong-sam, a spokesman for the air force, which planted the land mines in the 1960s around an air defence base on the mountain, said soldiers with metal detectors were waiting until rain stopped to begin searching. There were worries the soil might still be moving with land mines in it.

A Defence Ministry official said earlier that 10 mines could have been pushed down Wumyeon Mountain. Another ministry official, spokesman Kim Min-seok, played down the immediate risk because a concrete wall on the hillside could be stopping the mines from reaching rescue workers.

South Korea's military dug up many land mines on the mountain between 1999 and 2006, but about 10 couldn't be accounted for, officials said. Fences around the base have warnings about unaccounted land mines.

There were also fears of land mines in northern provinces hit by flooding and slides, prompting an order to begin search operations where needed.

The landslide in Seoul killed at least 16 people. About 5,000 firefighters, soldiers, police officers and others have mobilised to try to find any survivors and clean walls of mud piled in residential areas near the base of the mountain, emergency official Kim Wu-min said.

Bae Jin-sun, a 27-year-old who works in southern Seoul, said she was worried about the safety of rescue workers near the mountain.

"There is still the possibility of a land mine falling through the cracks," she said.